1. Field of the Invention
The present invention relates to a gas flow simulation method. More particularly, the present invention relates to a gas flow simulation method for simulating and visualizing the motion situation of a gas flow to check how a concavity formed on the surface of an object flying in a space affects the flow of a gas on the periphery of the concavity.
2. Description of the Related Art
To analyze the aerodynamic characteristic of many kinds of spheres such as a golf ball, a baseball ball, and the like, many kinds of apparatuses and methods have been proposed. In particular, in the case of the golf ball, a large number of dimples (concavities) formed on the surface thereof affect its aerodynamic characteristic greatly. Thus it is important to recognize the casual relation between the aerodynamic characteristic of the golf ball and the size, arrangement, and combination of the dimples.
To evaluate how the flight characteristic of the golf ball changes owing to the difference in the size, arrangement, and combination of the dimples formed on the surface of the golf ball, golf balls having different dimple specifications are made on an experimental basis and experiments of hitting the golf balls thus made are conducted to measure flight distances thereof and the like. In recent years, instead of the ball-hitting experiments, there are proposed methods of analyzing the aerodynamic characteristic of the golf ball placed in a wind tunnel by measuring the lift coefficient and drag coefficient thereof.
FIG. 14 shows the measuring apparatus, disclosed in Japanese Patent Application Laid-Open No. 6-194242, for analyzing the aerodynamic characteristic of the golf ball by utilizing the wind tunnel. In the measuring apparatus 1 placed in the wind tunnel together with the golf ball, the motor 3 rotates the aluminum shaft 2 having the object T such as the to-be-measured golf ball installed on its upper end, and the strain of the aluminum shaft 2 is detected by the strain-type detector 4, for detecting the axial three components of force, disposed on the periphery of the aluminum shaft 2. When the object T is rotated in an air current generated in the wind tunnel, the object T in the wind tunnel has a state pseudo to an actual flight state. The lift coefficient and drag coefficient of the object T are derived from a measured strain amount of the aluminum shaft 2 to analyze the flight characteristic of the object T. In the measurement which is performed by the measuring apparatus 1, air currents of various conditions are generated in the wind tunnel and the aerodynamic characteristic can be measured in various conditions.
The experiment of hitting the golf ball conducted on an experimental basis and the results measured by the measuring apparatus 1 utilizing the wind tunnel relate to the aerodynamic characteristic of the entire golf ball. Thus the measuring apparatus 1 has a problem that it is impossible to analyze in detail. More specifically, it is impossible to analyze how the air current is affected by the configuration, size, and arrangement of individual dimples formed on the surface of the golf ball. That is, in designing the golf ball, it is most important to know how the flow of the gas on the periphery of the dimple is affected by a particular arrangement of a newly added single dimple or a particular arrangement of plurality of newly added dimples. If it is possible to easily and promptly know the influence of each dimple on the air current on the periphery thereof, it is possible to make a golf ball as desired, by reflecting the content of the result obtained by the measurement.
However in the conventional measuring method, how the configuration of each dimple changes the flow of the air on the periphery thereof is unclear and only the resultant characteristic of the changed air current can be determined. That is, the conventional measuring method is incapable of clarifying the casual relation between the newly designed dimple and the aerodynamic characteristic. Therefore in developing the golf ball, many golf balls having different dimple configurations or different dimple arrangements are made on an experimental basis, and measurements as described above are made to merely estimate the influence of individual dimples on the gas flow, based on the aerodynamic characteristic of the entire golf ball. Thus the conventional measuring method is incapable of designing the golf ball efficiently.
Further the effect of the dimple is evaluated based on the estimation obtained from the measurement as described above and numerical values obtained from experience. Thus the conventional measuring method has a problem that the evaluation or the determination of the dimple lack objective accuracy. Therefore the newly designed golf ball is liable to have performance different from the desired performance. In this case, re-design is made to make a golf ball on an experimental basis and check the aerodynamic characteristic thereof. As such, the conventional measuring method has a problem that it takes much time and money to develop a golf ball having dimples newly designed configuration, size or arrangement.